Liquid pressure braking means for vehicles



1 April `14, 1936.

v E. B. BOUGHTON ETAL LIQUID PRESSURE BRAKING MEANS Fon VEHICLES Filed Aug. 9, 19.33

yf .a4 wu /I/Mw M w W7 -Mw Q lll ing cylinder.

Patented Apr. 14, 1936 LIQUID'PRESSUBE BEARING MEANS FOB VEHICLES A Edward Bishop noogntonaoa John 4norway, London, England, assignors to Lockheed Hydraulic Brake Company Limited, London, England Application ,August s, 193s, sonal No.-es4,445 1n Groot Brunn ootobor v, 1932 whims. (ci. 13s-isz) This invention relates to liquid pressure braking means for vehicles, and in particular to the cylinder and piston arrangementst the actual brakes, which, as a result'of pressure in a braking conduit, imparts the necessary movement and pressure to the brake elements.

As is well-known, it is usual to mount such an' actuating cylinder and piston upon the usual brake shoe carrying plate at the inner side thereof, so that it is totally or partly enclosed bythe brake drum. This location of the cylinder makes it inevitable that the cylinder and any liquid therein shall receive a considerable amount of heat which is generated when the brakes are in use, and, moreover, it is necessary to dismantle the brake in order to obtain access to the actuat- The present invention hasfor an object to `provide an improved arrangement of brake actuating cylinder and piston which shall not only render the cylinder very accessible but also ensure that it shall absorb litle or no heat from the brake.

To this end and according to the invention,`

Figure 1 i's a broken plan, partly in section, illustrating the liquid pressure means .for operating the brakes. ,f

Figure 2.is a view in elevation, partly in section, showing the mounting of the brake shoes and their cooperation with the brake operating means of the invention.

As illustrated in the drawing, the braking means of this invention includes a brake actuating cylinder II which is closed at'its outer end I2 near `which it is provided with an internallyl threaded bored, boss I3 for connection with abrake conduit (not shown), has a circumferential flange Il at its inner open end formed with apertures through which bolts I 5 are passedfto secure the cylinder II in position to the outer side of a brake plate I 6, i. e., to thatside of the latter remote from the brake shoes,\par ts of which are indicated at I1. Two of the bolts l5 whereby the cylinder I I is mounted in p osition have heads in the form of bifurcated lugs I8 which are formed with co-axial apertures through which are passed fulcrum pins I9 carrying yeach a rocker 20 equivaient to a bell-crank lever. Of the bolts I5, the two inquestion 'are so located in position that these rockers 2li may move about their fulcrum pins I9 in a common general plane diametrically of the cylinder II, the rockers 20 extending from their respective fulcrum pins I9 towards one another, i. e., radially of the axis of the cylinder II.

.nearer to the brake plate I6, is equal to substantially two-thirds of the internal diameter of the 1. actuating cylinder II, and midway between the two bolts I 5 which carry the rockers 20 the brake plate II is formed with an aperture 23 through which extends, from a piston 24 in said cylinder II,'a short thrust rod 25, the projecting end of which` is received, at the inner side of the brake plate I6, in a recess in'a compensating bridge member 26, within further oppositely, directed recesses 21 in which thosef ends of the rockers 20 nearer the brake plate I6 are received. Each brake shoe I'I is formed at one end with a pressure face 28, located normally substantially level with the centre line of one of theI vrocker carrying bolts I5, and the rockers 20 are so proportioned that those ends thereof remote from the 4vbroke plate ls are normally. in contact with the pressure faces 28 of the brake shoes I1, the action of the usual return spring 30 of which causes said faces 28 to bear upon the rockers 20, the rockers 20 in turn to bear at their other ends upon the compensating bridge member 26, this bridge member 26 in turn to bear upon the corresponding end of the thrust rod 25, and this.

thrust rod 25 to\bear against the piston 2l,

which latter is thus maintained normally in its.

oif position. The piston 2l has a sealing washer 24A which is maintained at all times in contact with the face of the piston 24 by means of a` spring- 24B. r l

When, during the actuating of the brakes, liquid is forced into the actuating cylinder II, the

piston 2l is urged towards the brake plate I6 and thus both rockers 20 are'moved about their iulcrum pins I9 away from said plate I6 and in brng'it into contact'with the brake drum be greater in the case of one shoe l1' than of the other, the compensating bridge member 26 will simply rock to an extent corresponding to the diierence in wear of the respective shoes I7.

It will further be observed that a brake actuating cylinder located according to the invention, is some distance away from the points Where heat is generated in the brakes and that, apart from this, it is exposed to a iiow of air which could not have access thereto were the cylinder located at the inner face of the brake plate Where it will inevitably be enclosed and shielded by the brake drum. With an arrangement according to the present inventiontherefore, there is little or no possibility of an undue rise in temperature of the braking liquid.

What we claim is:-

1. A uid pressure operated brake of the type including a Carrying plate and'brake shoes on one side of. said plate, comprising pressure responsive means carried by the plate'on the side opposite the brakeY shoes, an element projecting through the plate and actuated by said iluid responsive means, rockers pivotally supported in the plate and actuated by said element, said rockers bearing against but wholly free of other connection with the brake shoes, and a compensating .member arranged intermediate the element and rockers.

2. A iluid pressure operated brake of the type operated by the piston and extending through the carrying plate, rockers pivotally supported on; the carrying plate, and a. bridge plate for loperating the rockers and responsive to operative movement of the element, said bridge plate having rocking connection with the element.

3. A fluid pressure operated brake of the type including a carrying plate and brake shoes on actuated by the pressure responsive device and engaging the bridge plate.

4. A fluid pressure operated brake of the type including a carrying plate and brake shoes on one side of said plate, a pressure responsive device located on the opposite side o1' the plate, bolts connecting said device and plate and extending beyond the plate on the brake shoe carrying side 

